The present invention relates in general to conveying granular material, and more particularly, to conveying metered amounts of granular material.
Many systems employ granular or pulverulent material. Examples of such systems are dry cement handling systems, hopper container unloading systems, and the like.
Some of the systems used to move granular material from one location, such as a hopper or other storage device, to another location are required to deliver such granular material in metered amounts. The metered amounts can take the form of a controlled flow rate or the form of metered charges.
The inventor is aware of several devices which deliver metered amounts of granular material. Examples of such known devices are disclosed in U.S. Pat. Nos. 2,740,672, 2,890,079, 3,009,744 and 3,268,266. While all of the devices disclosed in these patents are somewhat efficient, they all suffer from drawbacks resulting from inefficient and inaccurately delivered material. The size of the charges of material delivered by these devices often varies beyond limit required for great accuracy, and such inaccuracies are not easily corrected, if they are correctable at all. Furthermore, some of the granular material delivered to these devices may be crushed by the device. Such crushed material may cause inaccuracies in the processes using the material delivered by the device.